METHANE

Anaerobic digestion captures methane in the process of decomposing organic waste. This is important as methane is a far more powerful greenhouse gas than CO2.

Robert Watson, the co-chair of the Intergovernmental Panel on Climate Change’s Third Assessment, recently wrote:

"The Copenhagen talks focused on the leading climate change culprit: CO2. But reversing global temperature increases by reducing carbon emissions will take many decades, if not centuries. Even if the largest cuts in CO2 contemplated in Copenhagen are implemented, it simply will not reverse the melting of ice already occurring...

The most obvious strategy is to make an all-out effort to reduce emissions of methane. Methane’s short life makes it especially interesting in the short run, given the pace of climate change. If we need to suppress temperature quickly in order to preserve glaciers, reducing methane can make an immediate impact. Compared to the massive requirements necessary to reduce CO2, cutting methane requires only modest investment.

Where we stop methane emissions, cooling follows within a decade, not centuries. That could make the difference for many fragile systems on the brink."

Robert Watson and Mahamed El-Ashry, “A Fast, Cheap Way to Cool the Planet,” The Wall Street Journal (December 29, 2009).

Bacteria to perform a thermodynamically tricky process: the anaerobic oxidation of methane.

Methane-induced melt-hole on a frozen lake in Alaska, April 2011.

"Methane is acknowledged as the second most important greenhouse gas produced by human activity after carbon dioxide and is responsible for about a fifth of warming effects. Its chief sources are landfill sites, fossil fuel energy and agriculture, particularly rice and livestock farming.

Its impact is higher than generally thought because previous estimates have not accounted for its interaction with airborne particles called aerosols, Nasa scientists found.

When this indirect effect of the potent greenhouse gas is included one tonne of methane has about 33 times as much effect on the climate over 100 years as a tonne of carbon dioxide, rather than 25 times as in standard estimates."